1. Field of Technology
The present invention relates to a wireless network system having access points or base stations at least capable of wireless transmission and terminals at least capable of wireless reception in a vehicle having a plurality of aisles.
2. Description of Related Art
Constructing a system connecting a plurality of terminals to a network in a building or vehicle has typically involved laying at least as many wired conductors as terminals.
While this method offers the advantage of highly reliable communication, the time and cost required to lay the lines and the work involved in subsequent maintenance are significant drawbacks.
Networks that connect wirelessly to the terminals are now available and are increasingly common. Wireless networks offer the advantage of requiring less time for installation and maintenance than conventional wired networks, and are therefore also less expensive. Wireless networks also eliminate the weight of the wires and the space needed to lay the wires, and are therefore particularly advantageous when installed in transportation vehicles.
Reflection of the radio waves by obstacles produces a phase shift in the signal waves that results in fading because the phase-shifted signals are then merged and result in a weakened reception level. Fading causes a loss of reception packets (errors), and narrows the usable bandwidth.
The literature is also silent on how the access points should be located in a vehicle having multiple aisles.
The general positioning of access points is described in Japanese Unexamined Patent Appl. Pub. H8-321799, Japanese Unexamined Patent Appl. Pub. H11-127096, and Japanese Unexamined Patent Appl. Pub. 2000-13853, but these documents are silent on the location of access points in a vehicle.
The access points could be located at equidistant intervals from the front to the back inside the passenger cabin.
However, if the signal strength of the wireless signals output from the access points is increased so that the signals can reach both ends of the vehicle, the wireless signals from two adjacent access points located one behind the other will interfere with each other, and signal quality will drop.